Interfacial tension is an important characteristic of a biological membrane because it determines its rigidity, thus affecting its stability. It is affected by factors such as medium pH and by the presence of certain substances, for example cholesterol, other lipids, fatty acids, amines, amino acids, or proteins, incorporated in the lipid bilayer. Here, the effects of various parameters to on interfacial tension values of bilayer lipid membranes are discussed.The mathematically derived and experimentally confirmed results presented in this paper are of importance to the interpretation of phenomena occurring in lipid bilayers. These results can lead to a better understanding of the physical properties of biological membranes. The simple interfacial tension method proposed herein may be successfully used to determine the interfacial tension values of 1:1 lipid-lipid, lipid-cholesterol, lipid-fatty acid, lipid-amine, and lipid-amino acid systems.